The lanternflies excrete a sugary substance that researchers call honeydew, said Julie Urban, an evolutionary biologist at Penn State. The honeydew then feeds a black mold that can cover plant leaves and block access to sunlight.

“Then the actual surface of the tree and the surrounding ground and understory are so blackened, to me it looks like someone burned it,” she said.

It’s still unclear what the economic damage will be for Pennsylvania’s agriculture industry. But Fred Strathmeyer, a deputy secretary at the Pennsylvania Department of Agriculture, said several farmers told him they fear they’ll go out of business if the lanternflies are not stopped.

And the insects are not just affecting fruit growers.

In the fall, Strathmeyer visited a daycare center close to Boyertown, Pennsylvania, where the lanternflies had swarmed.

After the center sprayed insecticide, “there were literally thousands and thousands of dead insects,” he said. “But there were still thousands and thousands of insects still flying around.”

The staff couldn’t let the children play outside.

Strathmeyer says the threat from the spotted lanternfly is right up there with the emerald ash borer and the brown marmorated stink bug.

Scientists are testing pesticides as a short-term solution, said Urban.

For the long term, they’re looking at parasitic wasps that could go after lanternfly larvae, as well as targeting some bacteria that lanternflies depend on. But Urban said it could take years before they come up with a long-term, biological solution.